US4933953A - Initial synchronization in spread spectrum receiver - Google Patents

Initial synchronization in spread spectrum receiver Download PDF

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Publication number
US4933953A
US4933953A US07/239,287 US23928788A US4933953A US 4933953 A US4933953 A US 4933953A US 23928788 A US23928788 A US 23928788A US 4933953 A US4933953 A US 4933953A
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signal
circuit
initial synchronization
correlation
synchronization
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US07/239,287
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Hideki Yagi
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KENWOOD 17-5 SHIBUYA 3-CHOME SHIBUYA-KU TOKYO JAPAN A CORP OF JAPAN KK
Kenwood KK
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Kenwood KK
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Assigned to KABUSHIKI KAISHA KENWOOD, 17-5, SHIBUYA 3-CHOME, SHIBUYA-KU, TOKYO, JAPAN, A CORP. OF JAPAN reassignment KABUSHIKI KAISHA KENWOOD, 17-5, SHIBUYA 3-CHOME, SHIBUYA-KU, TOKYO, JAPAN, A CORP. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: YAGI, HIDEKI
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/707Spread spectrum techniques using direct sequence modulation
    • H04B1/7073Synchronisation aspects
    • H04B1/7075Synchronisation aspects with code phase acquisition
    • H04B1/70755Setting of lock conditions, e.g. threshold

Abstract

An initial synchronization system for spread spectrum communication including a despreader-demodulator circuit for despreading and demodulating an input signal according to a despread control signal, a decoder circuit for decoding a data signal demodulated by the despreader-demodulator circuit and outputting a code synchronization signal when code synchronization is taken, a correlation detector circuit in response to the input signal for detecting the correlation of the input signal and generating the despread control signal and a correlation detection signal, and a control circuit for outputting an initial synchronization start signal to the correlation detector circuit so as to cause the correlation detector circuit to start the initial synchronization if the code synchronization signal is not generated within a predetermined period after the correlation detection signal was generated.

Description

FIELD OF THE INVENTION

The present invention relates to a spread spectrum communication system and, more particularly, to an initial synchronization circuit in a receiver of that system.

CONVENTIONAL ART

The spread spectrum system includes the following systems.

(1) DS (Direct Sequence) system

(2) FH (Frequency Hopping) system

(3) TH (Time Hopping) system

(4) Pulse coding FM system

(5) Hybrid system

In general, at present, the DS and FH systems are used, the TH system and pulse coding FM system are applied to the limited fields, and the hybrid system is being theoretically studied. The principle of the DS system will now be described. On the transmission side, the information signal is subjected to an ordinary modulation (primary modulation). The primary-modulated signal is then modulated by the spread pseudo noise code (PN code) of a wide band and transmitted as a wide band signal having a very small power density. This operation is called a spread modulation. On the reception side, the correlation with the received or incoming signal is derived by use of the same demodulating PN code as that on the transmission side. After the correlation was obtained, only the signal to be received is converted into the original primary-modulated signal of the narrow band. The other signals and interference signal become the wide band noises having a small power density. Only a desired signal is extracted by a filter. The primary modulation can use the analog system such as FM and the digital system such as PSK. In general, the PSK system by the pseudo noise (PN) code is used as the spread modulation.

It is required that the demodulating PN code which is generated on the reception side has the same bit constitution and the same phase as those of the PN code in the incoming or received spread spectrum signal. Therefore, the initial synchronization (synchronization trapping) is performed to made the phase of the PN code on the reception side coincide with the phase of the PN code in the incoming signal. Next, in order to keep the phase-coincident PN code on the reception side, the synchronization holding process is performed by a delay-locked loop circuit (DLL).

For an initial synchronization, the phase state of the PN code in the received signal is detected by a correlation detection circuit (PN SYNC) and the correlation detection output is used to take the initial synchronization. After the initial synchronization, the synchronization is kept by a delay-locked loop in a despreader-demodulator circuit.

In a spread spectrum communication system, it is required to conduct an initial synchronization at a high speed.

This is also true particularly for the case where a C/N ratio is degraded and the correlation outputs are being fluctuating.

It is an object of the present invention to provide an initial synchronization system for spread spectrum communication which can realize an initial synchronization at high speed even in the case where a C/N ratio is degraded and the correlation outputs are being fluctuating.

SUMMARY OF THE INVENTION

To solve the above problems, the initial synchronization system for spread spectrum communication according to the present invention comprises a despreader-demodulator circuit for despreading and demodulating an input signal according to a despread control signal, a decoder circuit for decoding a data signal demodulated by the despreader-demodulator circuit and outputting a code synchronization signal when code synchronization is taken, a correlation detector circuit in response to the input signal for detecting the correlation of the input signal and generating the despread control signal and a correlation detection signal, and a control circuit for outputting an initial synchronization start signal to the correlation detector circuit so as to cause the correlation detector circuit to start the initial synchronization if the code synchronization signal is not generated within a predetermined period after the correlation detection signal was generated.

The case where the code synchronization signal is not generated within a predetermined period after the correlation detection signal was generated corresponds to the case where the initial synchronization was not taken. For such a case, an initial synchronization start signal is again supplied to the correlation detector circuit.

The predetermined period is set slightly longer than the period required in despreading/demodulating and in code synchronization for decoding so that the initial synchronization can be taken efficiently even in the case where a C/N ratio is degraded and the correlation outputs are being fluctuating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the circuit arrangement of an embodiment of the initial synchronization system of this invention; and

FIG. 2 is a flow chart used for explaining the operation of the embodiment shown in FIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENT

FIG. 1 is a block diagram showing the circuit arrangement of the embodiment according to the present invention.

A despreader-demodulator circuit 1 starts despreading and demodulating an inputted intermediate frequency signal A upon reception of a despread control signal B, and outputs a demodulated data signal C.

A correlation detector circuit 3 starts detecting a correlation of the inputted intermediate frequency signal A upon reception of an initial synchronization start signal D, and outputs a correlation detection signal E and the despread control signal B when a correlation is detected.

An error correction decoder circuit 2 decodes the demodulated data signal C to output decoded data F, and output a code synchronization signal G when a code synchronization is taken.

A control circuit 4 causes a timer 5 to start every time the former receives the correlation detection signal E, and checks if the code synchronization signal G is generated within a predetermined period set in the timer 5. If the code synchronization signal G is not detected within the predetermined period, the control circuit 4 generates the initial synchronization start signal D to repeat the operation to check if the code synchronization signal G is generated or not.

The operation of the embodiment of this invention constructed as above will be described with reference to the flow chart shown in FIG. 2.

As an initial synchronization is instructed to the control circuit 4, it outputs an initial synchronization start signal D to the correlation detector circuit 3 (step a). The correlation detector circuit 3 starts a correlation detection operation, and the flow waits for a detection of a correlation (step b). Upon detection of a correlation, the correlation detector circuit 3 outputs a correlation detection signal E to the control circuit 4 which in turn causes the timer 5 to start its counting operation (step c).

Simultaneously with the detection of a correlation, the correlation detector circuit 3 also outputs a despread control signal B to the despreader-demodulator circuit 1 which in turn starts despreading and demodulating an inputted intermediate frequency signal A to output a demodulated data signal C. The demodulated data signal C is decoded by the error correction decoder circuit 2 to output decoded data F. When the code synchronization is taken at the error correction decoder circuit 2, it outputs a code synchronization signal G to the control circuit 4. It is checked if the code synchronization signal G is sent to the control circuit 4 within the predetermined period set in the timer 5 (step d, e). The predetermined period set in the timer 5 is slightly longer than the period required in despreading/demodulating and in code synchronization for decoding. As a result, if the code synchronization signal G is sent within the predetermined period set in the timer 5, it means that the initial synchronization was completed. However, if the code synchronization signal G is not sent within the predetermined period, the initial synchronization start signal D is again sent from the control circuit 4 to the correlation detector circuit 3 to return to step a for repeating the initial synchronization.

The control circuit 4 may be constructed of a microcomputer. Instead of using the code synchronization signal G outputted from the error correction decoder circuit 2, a lock signal from the despreader-demodulator circuit 1 may be used to achieve the same processing.

As appreciated from the foregoing description of this invention, it is checked if the code synchronization signal is generated within a predetermined period after a correlation detection signal was generated. If the code synchronization signal is not generated within the predetermined period, an initial synchronization start signal is again outputted to repeat the initial correlation detection operation. Therefore, even in the case where a C/N ratio is degraded and the correlation detection outputs are being fluctuating, the initial synchronization can be taken efficiently at high speed by repeating the correlation detection operation. Specifically, the predetermined period is set slightly longer than the period required in despreading/demodulating and in code synchronization for decoding so that the initial synchronization can be efficiently achieved at high speed.

Without the arrangement described as above, the despreading/demodulating and decoding are carried out even if the initial synchronization is not taken, thus resulting in man false detections.

Claims (4)

What is claimed is:
1. An initial synchronization system for spread spectrum communication comprising:
a despreader-demodulator circuit for despreading and demodulating an input spread spectrum signal according to a despread control signal to reproduce a data signal;
a decoder circuit for error-correction-decoding the data signal and outputting a code synchronization signal when code synchronization is taken;
a correlation detector circuit in response to an initial synchronization start signal for detecting the correlation of the input spread spectrum signal for an initial synchronization and generating the despread control signal and a correlation detection signal; and
a control circuit for outputting the initial synchronization start signal to said correlation detector circuit so as to cause said correlation detector circuit to restart the initial synchronization if the code synchronization signal is not generated within a predetermined period after the correlation detection signal was generated.
2. An initial synchronization system according to claim 1 further comprising timer means provided with a timer setting period which is equal to said predetermined period.
3. An initial synchronization system according to claim 2, wherein said control circuit in response to the correlation detection signal starts said timer.
4. An initial synchronization system according to claim 1, wherein said predetermined period is set slightly longer than the interval time necessary for the despreading-demodulation in said despreader-demodulator circuit and the code synchronizing in said decoder circuit.
US07/239,287 1987-09-10 1988-09-01 Initial synchronization in spread spectrum receiver Expired - Lifetime US4933953A (en)

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JP62-225396 1987-09-10
JP62225396A JPH0671241B2 (en) 1987-09-10 1987-09-10 Initial synchronization method of spread-spectrum communication

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Cited By (56)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5103461A (en) * 1989-06-29 1992-04-07 Symbol Technologies, Inc. Signal quality measure in packet data communication
US5142550A (en) * 1989-06-29 1992-08-25 Symbol Technologies, Inc. Packet data communication system
US5157687A (en) * 1989-06-29 1992-10-20 Symbol Technologies, Inc. Packet data communication network
US5228056A (en) * 1990-12-14 1993-07-13 Interdigital Technology Corporation Synchronous spread-spectrum communications system and method
US5280498A (en) * 1989-06-29 1994-01-18 Symbol Technologies, Inc. Packet data communication system
US5345467A (en) * 1991-07-10 1994-09-06 Interdigital Technology Corp. CDMA cellular hand-off apparatus and method
US5393965A (en) * 1990-11-13 1995-02-28 Symbol Technologies, Inc. Flexible merchandise checkout and inventory management system
US5401944A (en) * 1990-11-20 1995-03-28 Symbol Technologies, Inc. Traveler security and luggage control system
US5528621A (en) * 1989-06-29 1996-06-18 Symbol Technologies, Inc. Packet data communication system
US5724384A (en) * 1994-07-14 1998-03-03 Samsung Electronics Co., Ltd. PN code sync device using an adaptive threshold
US5729571A (en) * 1994-06-29 1998-03-17 Samsung Electronics Co. Ltd. Non-coherent digital receiver of a spread spectrum communication system
US5974039A (en) * 1990-12-05 1999-10-26 Interdigital Technology Corporation CDMA communications and geolocation system and method
US6426916B2 (en) 1990-04-18 2002-07-30 Rambus Inc. Memory device having a variable data output length and a programmable register
US6570814B2 (en) 1990-04-18 2003-05-27 Rambus Inc. Integrated circuit device which outputs data after a latency period transpires
US6614864B1 (en) 1999-10-12 2003-09-02 Itran Communications Ltd. Apparatus for and method of adaptive synchronization in a spread spectrum communications receiver
US6684285B2 (en) 1990-04-18 2004-01-27 Rambus Inc. Synchronous integrated circuit device
US20050059405A1 (en) * 2003-09-17 2005-03-17 Trapeze Networks, Inc. Simulation driven wireless LAN planning
US20050059406A1 (en) * 2003-09-17 2005-03-17 Trapeze Networks, Inc. Wireless LAN measurement feedback
US20050180358A1 (en) * 2004-02-13 2005-08-18 Trapeze Networks, Inc. Station mobility between access points
US20060176868A1 (en) * 1990-12-05 2006-08-10 Interdigital Technology Corporation Cellular CDMA notch filter
US20060248331A1 (en) * 2005-03-15 2006-11-02 Dan Harkins System and method for distributing keys in a wireless network
US20070086398A1 (en) * 2005-10-13 2007-04-19 Manish Tiwari Identity-based networking
US20070096847A1 (en) * 2005-10-28 2007-05-03 Trutna William R Jr Spread-spectrum radio utilizing MEMS components
US20070106722A1 (en) * 2005-10-27 2007-05-10 Zeldin Paul E Non-persistent and persistent information setting method and system for inter-process communication
US20070258448A1 (en) * 2006-05-03 2007-11-08 Hu Tyng J A System and method for restricting network access using forwarding databases
US20070260720A1 (en) * 2006-05-03 2007-11-08 Morain Gary E Mobility domain
US20070268516A1 (en) * 2006-05-19 2007-11-22 Jamsheed Bugwadia Automated policy-based network device configuration and network deployment
US20070268515A1 (en) * 2006-05-19 2007-11-22 Yun Freund System and method for automatic configuration of remote network switch and connected access point devices
US20070268506A1 (en) * 2006-05-19 2007-11-22 Paul Zeldin Autonomous auto-configuring wireless network device
US20070268514A1 (en) * 2006-05-19 2007-11-22 Paul Zeldin Method and business model for automated configuration and deployment of a wireless network in a facility without network administrator intervention
US20070281711A1 (en) * 2006-06-01 2007-12-06 Sudheer Poorna Chandra Matta Wireless load balancing across bands
US20070287500A1 (en) * 2006-06-12 2007-12-13 Philip Riley Tuned directional antennas
US20080013481A1 (en) * 2006-07-17 2008-01-17 Michael Terry Simons Wireless VLAN system and method
US20080096575A1 (en) * 2006-10-16 2008-04-24 Trapeze Networks, Inc. Load balancing
US20080107077A1 (en) * 2006-11-03 2008-05-08 James Murphy Subnet mobility supporting wireless handoff
US20090073905A1 (en) * 2007-09-18 2009-03-19 Trapeze Networks, Inc. High level instruction convergence function
US7573859B2 (en) 2005-10-13 2009-08-11 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US20090274060A1 (en) * 2005-10-13 2009-11-05 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US20090293106A1 (en) * 2005-03-31 2009-11-26 Trapeze Networks, Inc. Method and apparatus for controlling wireless network access privileges based on wireless client location
US7724703B2 (en) 2005-10-13 2010-05-25 Belden, Inc. System and method for wireless network monitoring
US20100329177A1 (en) * 2006-06-09 2010-12-30 James Murphy Ap-local dynamic switching
US7865713B2 (en) 2006-12-28 2011-01-04 Trapeze Networks, Inc. Application-aware wireless network system and method
US7873061B2 (en) 2006-12-28 2011-01-18 Trapeze Networks, Inc. System and method for aggregation and queuing in a wireless network
US7912982B2 (en) 2006-06-09 2011-03-22 Trapeze Networks, Inc. Wireless routing selection system and method
US8150357B2 (en) 2008-03-28 2012-04-03 Trapeze Networks, Inc. Smoothing filter for irregular update intervals
US8238298B2 (en) 2008-08-29 2012-08-07 Trapeze Networks, Inc. Picking an optimal channel for an access point in a wireless network
US8238942B2 (en) 2007-11-21 2012-08-07 Trapeze Networks, Inc. Wireless station location detection
US8340110B2 (en) 2006-09-15 2012-12-25 Trapeze Networks, Inc. Quality of service provisioning for wireless networks
US8474023B2 (en) 2008-05-30 2013-06-25 Juniper Networks, Inc. Proactive credential caching
US8542836B2 (en) 2010-12-01 2013-09-24 Juniper Networks, Inc. System, apparatus and methods for highly scalable continuous roaming within a wireless network
US8638762B2 (en) 2005-10-13 2014-01-28 Trapeze Networks, Inc. System and method for network integrity
US8818322B2 (en) 2006-06-09 2014-08-26 Trapeze Networks, Inc. Untethered access point mesh system and method
US8902904B2 (en) 2007-09-07 2014-12-02 Trapeze Networks, Inc. Network assignment based on priority
US8966018B2 (en) 2006-05-19 2015-02-24 Trapeze Networks, Inc. Automated network device configuration and network deployment
US8978105B2 (en) 2008-07-25 2015-03-10 Trapeze Networks, Inc. Affirming network relationships and resource access via related networks
US9191799B2 (en) 2006-06-09 2015-11-17 Juniper Networks, Inc. Sharing data between wireless switches system and method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4121159A (en) * 1970-11-06 1978-10-17 Siemens Aktiengesellschaft Method for the synchronization of a transmission path
US4351064A (en) * 1970-10-30 1982-09-21 Westinghouse Electric Corp. Communication
US4752939A (en) * 1986-09-03 1988-06-21 Hughes Aircraft Company Hidden preamble for frequency hopped synchronization

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4351064A (en) * 1970-10-30 1982-09-21 Westinghouse Electric Corp. Communication
US4121159A (en) * 1970-11-06 1978-10-17 Siemens Aktiengesellschaft Method for the synchronization of a transmission path
US4752939A (en) * 1986-09-03 1988-06-21 Hughes Aircraft Company Hidden preamble for frequency hopped synchronization

Cited By (106)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5479441A (en) * 1989-06-29 1995-12-26 Symbol Technologies Packet data communication system
US5142550A (en) * 1989-06-29 1992-08-25 Symbol Technologies, Inc. Packet data communication system
US5157687A (en) * 1989-06-29 1992-10-20 Symbol Technologies, Inc. Packet data communication network
US5103461A (en) * 1989-06-29 1992-04-07 Symbol Technologies, Inc. Signal quality measure in packet data communication
US5280498A (en) * 1989-06-29 1994-01-18 Symbol Technologies, Inc. Packet data communication system
US5528621A (en) * 1989-06-29 1996-06-18 Symbol Technologies, Inc. Packet data communication system
US6598171B1 (en) 1990-04-18 2003-07-22 Rambus Inc. Integrated circuit I/O using a high performance bus interface
US6684285B2 (en) 1990-04-18 2004-01-27 Rambus Inc. Synchronous integrated circuit device
US6570814B2 (en) 1990-04-18 2003-05-27 Rambus Inc. Integrated circuit device which outputs data after a latency period transpires
US6728819B2 (en) 1990-04-18 2004-04-27 Rambus Inc. Synchronous memory device
US20050030802A1 (en) * 1990-04-18 2005-02-10 Rambus Inc. Memory module including an integrated circuit device
US20050033903A1 (en) * 1990-04-18 2005-02-10 Rambus Inc. Integrated circuit device
US6751696B2 (en) 1990-04-18 2004-06-15 Rambus Inc. Memory device having a programmable register
US20060039213A1 (en) * 1990-04-18 2006-02-23 Rambus Inc. Integrated circuit I/O using a high performance bus interface
US6426916B2 (en) 1990-04-18 2002-07-30 Rambus Inc. Memory device having a variable data output length and a programmable register
US6715020B2 (en) 1990-04-18 2004-03-30 Rambus Inc. Synchronous integrated circuit device
US6697295B2 (en) 1990-04-18 2004-02-24 Rambus Inc. Memory device having a programmable register
US6807598B2 (en) 1990-04-18 2004-10-19 Rambus Inc. Integrated circuit device having double data rate capability
US6584037B2 (en) 1990-04-18 2003-06-24 Rambus Inc Memory device which samples data after an amount of time transpires
US5393965A (en) * 1990-11-13 1995-02-28 Symbol Technologies, Inc. Flexible merchandise checkout and inventory management system
US5401944A (en) * 1990-11-20 1995-03-28 Symbol Technologies, Inc. Traveler security and luggage control system
US6917601B2 (en) 1990-12-05 2005-07-12 Interdigital Technology Corporation Spread spectrum remote unit
US7020114B2 (en) 1990-12-05 2006-03-28 Interdigital Technology Corporation Spread spectrum communication system and method using a reference signal and a plurality of message signals
US20020126639A1 (en) * 1990-12-05 2002-09-12 Interdigital Technology Corporation Spread spectrum communications using a reference and a message signal system and method
US20020122399A1 (en) * 1990-12-05 2002-09-05 Interdigital Technology Corporation Spread spectrum remote unit
US20020118660A1 (en) * 1990-12-05 2002-08-29 Interdigital Technology Corporation Spread spectrum base station
US6396824B1 (en) 1990-12-05 2002-05-28 Interdigital Technology Corporation CDMA communications and geolocation system and method
US5974039A (en) * 1990-12-05 1999-10-26 Interdigital Technology Corporation CDMA communications and geolocation system and method
US20020126638A1 (en) * 1990-12-05 2002-09-12 Interdigital Technology Corporation Spread spectrum communication system and method using a reference signal and a plurality of message signals
US20060176868A1 (en) * 1990-12-05 2006-08-10 Interdigital Technology Corporation Cellular CDMA notch filter
US7099292B2 (en) 1990-12-05 2006-08-29 Interdigital Technology Corporation Spread spectrum communications using a reference and a message signal system and method
US6925071B2 (en) 1990-12-05 2005-08-02 Interdigital Technology Corporation Spread spectrum base station
US20070002934A1 (en) * 1990-12-05 2007-01-04 Interdigital Technology Corporation Spread spectrum reception using a reference code signal
US5228056A (en) * 1990-12-14 1993-07-13 Interdigital Technology Corporation Synchronous spread-spectrum communications system and method
US5345467A (en) * 1991-07-10 1994-09-06 Interdigital Technology Corp. CDMA cellular hand-off apparatus and method
US5729571A (en) * 1994-06-29 1998-03-17 Samsung Electronics Co. Ltd. Non-coherent digital receiver of a spread spectrum communication system
US5724384A (en) * 1994-07-14 1998-03-03 Samsung Electronics Co., Ltd. PN code sync device using an adaptive threshold
US6614864B1 (en) 1999-10-12 2003-09-02 Itran Communications Ltd. Apparatus for and method of adaptive synchronization in a spread spectrum communications receiver
US20050059405A1 (en) * 2003-09-17 2005-03-17 Trapeze Networks, Inc. Simulation driven wireless LAN planning
US20050059406A1 (en) * 2003-09-17 2005-03-17 Trapeze Networks, Inc. Wireless LAN measurement feedback
US20070189222A1 (en) * 2004-02-13 2007-08-16 Trapeze Networks, Inc. Station mobility between access points
US20050180358A1 (en) * 2004-02-13 2005-08-18 Trapeze Networks, Inc. Station mobility between access points
US7221927B2 (en) 2004-02-13 2007-05-22 Trapeze Networks, Inc. Station mobility between access points
US8635444B2 (en) 2005-03-15 2014-01-21 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US8161278B2 (en) 2005-03-15 2012-04-17 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US7529925B2 (en) 2005-03-15 2009-05-05 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US20060248331A1 (en) * 2005-03-15 2006-11-02 Dan Harkins System and method for distributing keys in a wireless network
US20090293106A1 (en) * 2005-03-31 2009-11-26 Trapeze Networks, Inc. Method and apparatus for controlling wireless network access privileges based on wireless client location
US20070086398A1 (en) * 2005-10-13 2007-04-19 Manish Tiwari Identity-based networking
US8116275B2 (en) 2005-10-13 2012-02-14 Trapeze Networks, Inc. System and network for wireless network monitoring
US8218449B2 (en) 2005-10-13 2012-07-10 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US7573859B2 (en) 2005-10-13 2009-08-11 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US7724703B2 (en) 2005-10-13 2010-05-25 Belden, Inc. System and method for wireless network monitoring
US8457031B2 (en) 2005-10-13 2013-06-04 Trapeze Networks, Inc. System and method for reliable multicast
US8270408B2 (en) 2005-10-13 2012-09-18 Trapeze Networks, Inc. Identity-based networking
US8638762B2 (en) 2005-10-13 2014-01-28 Trapeze Networks, Inc. System and method for network integrity
US20090274060A1 (en) * 2005-10-13 2009-11-05 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US8514827B2 (en) 2005-10-13 2013-08-20 Trapeze Networks, Inc. System and network for wireless network monitoring
US7551619B2 (en) 2005-10-13 2009-06-23 Trapeze Networks, Inc. Identity-based networking
US8250587B2 (en) 2005-10-27 2012-08-21 Trapeze Networks, Inc. Non-persistent and persistent information setting method and system for inter-process communication
US20070106722A1 (en) * 2005-10-27 2007-05-10 Zeldin Paul E Non-persistent and persistent information setting method and system for inter-process communication
US7429904B2 (en) * 2005-10-28 2008-09-30 Avago Technologies Wireless Ip (Singapore) Pte Ltd Spread-spectrum radio utilizing MEMS components
US20070096847A1 (en) * 2005-10-28 2007-05-03 Trutna William R Jr Spread-spectrum radio utilizing MEMS components
US7558266B2 (en) 2006-05-03 2009-07-07 Trapeze Networks, Inc. System and method for restricting network access using forwarding databases
US8964747B2 (en) 2006-05-03 2015-02-24 Trapeze Networks, Inc. System and method for restricting network access using forwarding databases
US20070260720A1 (en) * 2006-05-03 2007-11-08 Morain Gary E Mobility domain
US20070258448A1 (en) * 2006-05-03 2007-11-08 Hu Tyng J A System and method for restricting network access using forwarding databases
US8966018B2 (en) 2006-05-19 2015-02-24 Trapeze Networks, Inc. Automated network device configuration and network deployment
US20070268516A1 (en) * 2006-05-19 2007-11-22 Jamsheed Bugwadia Automated policy-based network device configuration and network deployment
US20070268514A1 (en) * 2006-05-19 2007-11-22 Paul Zeldin Method and business model for automated configuration and deployment of a wireless network in a facility without network administrator intervention
US20070268506A1 (en) * 2006-05-19 2007-11-22 Paul Zeldin Autonomous auto-configuring wireless network device
US20070268515A1 (en) * 2006-05-19 2007-11-22 Yun Freund System and method for automatic configuration of remote network switch and connected access point devices
US7577453B2 (en) 2006-06-01 2009-08-18 Trapeze Networks, Inc. Wireless load balancing across bands
US20070281711A1 (en) * 2006-06-01 2007-12-06 Sudheer Poorna Chandra Matta Wireless load balancing across bands
US8818322B2 (en) 2006-06-09 2014-08-26 Trapeze Networks, Inc. Untethered access point mesh system and method
US20100329177A1 (en) * 2006-06-09 2010-12-30 James Murphy Ap-local dynamic switching
US7912982B2 (en) 2006-06-09 2011-03-22 Trapeze Networks, Inc. Wireless routing selection system and method
US9838942B2 (en) 2006-06-09 2017-12-05 Trapeze Networks, Inc. AP-local dynamic switching
US9258702B2 (en) 2006-06-09 2016-02-09 Trapeze Networks, Inc. AP-local dynamic switching
US9191799B2 (en) 2006-06-09 2015-11-17 Juniper Networks, Inc. Sharing data between wireless switches system and method
US10327202B2 (en) 2006-06-09 2019-06-18 Trapeze Networks, Inc. AP-local dynamic switching
US7865213B2 (en) 2006-06-12 2011-01-04 Trapeze Networks, Inc. Tuned directional antennas
US7844298B2 (en) 2006-06-12 2010-11-30 Belden Inc. Tuned directional antennas
US20100103059A1 (en) * 2006-06-12 2010-04-29 Trapeze Networks, Inc. Tuned directional antennas
US20070287500A1 (en) * 2006-06-12 2007-12-13 Philip Riley Tuned directional antennas
US8581790B2 (en) 2006-06-12 2013-11-12 Trapeze Networks, Inc. Tuned directional antennas
US20100113098A1 (en) * 2006-06-12 2010-05-06 Trapeze Networks, Inc. Tuned directional antennas
US20080013481A1 (en) * 2006-07-17 2008-01-17 Michael Terry Simons Wireless VLAN system and method
US7724704B2 (en) 2006-07-17 2010-05-25 Beiden Inc. Wireless VLAN system and method
US8340110B2 (en) 2006-09-15 2012-12-25 Trapeze Networks, Inc. Quality of service provisioning for wireless networks
US20080096575A1 (en) * 2006-10-16 2008-04-24 Trapeze Networks, Inc. Load balancing
US8446890B2 (en) 2006-10-16 2013-05-21 Juniper Networks, Inc. Load balancing
US8072952B2 (en) 2006-10-16 2011-12-06 Juniper Networks, Inc. Load balancing
US20080107077A1 (en) * 2006-11-03 2008-05-08 James Murphy Subnet mobility supporting wireless handoff
US7873061B2 (en) 2006-12-28 2011-01-18 Trapeze Networks, Inc. System and method for aggregation and queuing in a wireless network
US7865713B2 (en) 2006-12-28 2011-01-04 Trapeze Networks, Inc. Application-aware wireless network system and method
US8670383B2 (en) 2006-12-28 2014-03-11 Trapeze Networks, Inc. System and method for aggregation and queuing in a wireless network
US8902904B2 (en) 2007-09-07 2014-12-02 Trapeze Networks, Inc. Network assignment based on priority
US20090073905A1 (en) * 2007-09-18 2009-03-19 Trapeze Networks, Inc. High level instruction convergence function
US8509128B2 (en) 2007-09-18 2013-08-13 Trapeze Networks, Inc. High level instruction convergence function
US8238942B2 (en) 2007-11-21 2012-08-07 Trapeze Networks, Inc. Wireless station location detection
US8150357B2 (en) 2008-03-28 2012-04-03 Trapeze Networks, Inc. Smoothing filter for irregular update intervals
US8474023B2 (en) 2008-05-30 2013-06-25 Juniper Networks, Inc. Proactive credential caching
US8978105B2 (en) 2008-07-25 2015-03-10 Trapeze Networks, Inc. Affirming network relationships and resource access via related networks
US8238298B2 (en) 2008-08-29 2012-08-07 Trapeze Networks, Inc. Picking an optimal channel for an access point in a wireless network
US8542836B2 (en) 2010-12-01 2013-09-24 Juniper Networks, Inc. System, apparatus and methods for highly scalable continuous roaming within a wireless network

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